Outline

Introduction: Viruses are associated with multiple cancer types in human. In 1984, Newell and colleagues were the first to suggest that testicular cancer might have a viral etiology since it showed similar characteristics to Hodgkin’s lymphoma which is caused by EBV infection.

Materials and methods: We have conducted a systematic literature review and meta-analysis to investigate any possible association between viral infections (EBV, CMV, Parvovirus B19, HPV and HIV) and testicular cancer. The literature search was conducted using both the MEDLINE and EMBASE databases from 1985 through June 2010. The references of the located articles were also searched for more relevant literature. A total of 21 articles were found discussing the association of testicular cancer and infection by multiple virus types (EBV, CMV, Parvovirus B19, HPV and HIV), they were included in the meta-analysis. All epidemiological and laboratory studies were included since most of the studies were laboratory studies and they provided better testing and localization of infections.

Results: For infection with EBV, the pooled OR from 7 studies showed a slightly increased OR=1.62 (95% CI 1.15–2.29). For CMV (4 studies), OR=2.99 (95% CI 1.87–4.79). For Parvovirus (4 studies), OR=1.50 (95% CI 0.96–2.34). And for HIV (3 studies), OR=1.79 (95% CI 1.45–2.21). No pooling was possible for HPV studies since there were only two. The heterogeneity between the included studies was high for the pooled OR, for EBV (IÂ²=89%), CMV (IÂ²=57%), Parvovirus B19 (IÂ²=81%). While the studies for HIV infection showed a very low heterogeneity (IÂ²=0%).

Discussion and conclusion: There are some hints at possible association between viral infection and testicular cancer later in life. The very high heterogeneity between the studies could be caused by the use of both epidemiological and non-epidemiological studies as well as the different methods used to investigate viral infection and the precision of the methods. For HIV, not all the located studies contained enough information to be included in the meta-analysis; inclusion of only some of the studies could have resulted in the low heterogeneity reported. More epidemiological studies with better testing methods are needed to verify any possible association.